The ratio of red to green stamps that Esther had was 5 : 3. The cost of each of the red stamps was $2 and the cost of each of the green stamps was $7. Esther sold 60% of the red stamps and the total cost of the unsold stamps was $275. How many green stamps did she have left?
| |
Red stamps |
Green stamps |
| Before |
5 u |
3 u |
| Change |
- 3 u |
|
| After |
2 u |
3 u |
Number of red stamps sold
= 60% x 5 u
=
60100 x 5 u
= 3 u
| |
Red stamps |
Green stamps |
Total |
| Number |
2 u |
3 u |
|
| Value |
$2 |
$7 |
|
| Total value |
4 u |
21 u |
$275 |
Total cost of unsold stamps
= 4 u + 21 u
= 25 u
25 u = 275
1 u = 275 ÷ 25 = 11
Number of green stamps that Esther had left
= 21 u
= 21 x 11
= 231
Answer(s): 231
